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Diffstat (limited to 'contrib/luasrcdiet/lua/optparser.lua')
| -rw-r--r-- | contrib/luasrcdiet/lua/optparser.lua | 564 |
1 files changed, 564 insertions, 0 deletions
diff --git a/contrib/luasrcdiet/lua/optparser.lua b/contrib/luasrcdiet/lua/optparser.lua new file mode 100644 index 0000000000..cfe6cc1013 --- /dev/null +++ b/contrib/luasrcdiet/lua/optparser.lua @@ -0,0 +1,564 @@ +--[[-------------------------------------------------------------------- + + optparser.lua: does parser-based optimizations + This file is part of LuaSrcDiet. + + Copyright (c) 2008 Kein-Hong Man <khman@users.sf.net> + The COPYRIGHT file describes the conditions + under which this software may be distributed. + + See the ChangeLog for more information. + +----------------------------------------------------------------------]] + +--[[-------------------------------------------------------------------- +-- NOTES: +-- * For more parser-based optimization ideas, see the TODO items or +-- look at technotes.txt. +-- * The processing load is quite significant, but since this is an +-- off-line text processor, I believe we can wait a few seconds. +-- * TODO: might process "local a,a,a" wrongly... need tests! +-- * TODO: remove position handling if overlapped locals (rem < 0) +-- needs more study, to check behaviour +-- * TODO: there are probably better ways to do allocation, e.g. by +-- choosing better methods to sort and pick locals... +-- * TODO: we don't need 53*63 two-letter identifiers; we can make +-- do with significantly less depending on how many that are really +-- needed and improve entropy; e.g. 13 needed -> choose 4*4 instead +----------------------------------------------------------------------]] + +local base = _G +local string = require "string" +local table = require "table" +module "optparser" + +---------------------------------------------------------------------- +-- Letter frequencies for reducing symbol entropy (fixed version) +-- * Might help a wee bit when the output file is compressed +-- * See Wikipedia: http://en.wikipedia.org/wiki/Letter_frequencies +-- * We use letter frequencies according to a Linotype keyboard, plus +-- the underscore, and both lower case and upper case letters. +-- * The arrangement below (LC, underscore, %d, UC) is arbitrary. +-- * This is certainly not optimal, but is quick-and-dirty and the +-- process has no significant overhead +---------------------------------------------------------------------- + +local LETTERS = "etaoinshrdlucmfwypvbgkqjxz_ETAOINSHRDLUCMFWYPVBGKQJXZ" +local ALPHANUM = "etaoinshrdlucmfwypvbgkqjxz_0123456789ETAOINSHRDLUCMFWYPVBGKQJXZ" + +-- names or identifiers that must be skipped +-- * the first two lines are for keywords +local SKIP_NAME = {} +for v in string.gmatch([[ +and break do else elseif end false for function if in +local nil not or repeat return then true until while +self]], "%S+") do + SKIP_NAME[v] = true +end + +------------------------------------------------------------------------ +-- variables and data structures +------------------------------------------------------------------------ + +local toklist, seminfolist, -- token lists + globalinfo, localinfo, -- variable information tables + globaluniq, localuniq, -- unique name tables + var_new, -- index of new variable names + varlist -- list of output variables + +---------------------------------------------------------------------- +-- preprocess information table to get lists of unique names +---------------------------------------------------------------------- + +local function preprocess(infotable) + local uniqtable = {} + for i = 1, #infotable do -- enumerate info table + local obj = infotable[i] + local name = obj.name + -------------------------------------------------------------------- + if not uniqtable[name] then -- not found, start an entry + uniqtable[name] = { + decl = 0, token = 0, size = 0, + } + end + -------------------------------------------------------------------- + local uniq = uniqtable[name] -- count declarations, tokens, size + uniq.decl = uniq.decl + 1 + local xref = obj.xref + local xcount = #xref + uniq.token = uniq.token + xcount + uniq.size = uniq.size + xcount * #name + -------------------------------------------------------------------- + if obj.decl then -- if local table, create first,last pairs + obj.id = i + obj.xcount = xcount + if xcount > 1 then -- if ==1, means local never accessed + obj.first = xref[2] + obj.last = xref[xcount] + end + -------------------------------------------------------------------- + else -- if global table, add a back ref + uniq.id = i + end + -------------------------------------------------------------------- + end--for + return uniqtable +end + +---------------------------------------------------------------------- +-- calculate actual symbol frequencies, in order to reduce entropy +-- * this may help further reduce the size of compressed sources +-- * note that since parsing optimizations is put before lexing +-- optimizations, the frequency table is not exact! +-- * yes, this will miss --keep block comments too... +---------------------------------------------------------------------- + +local function recalc_for_entropy(option) + local byte = string.byte + local char = string.char + -- table of token classes to accept in calculating symbol frequency + local ACCEPT = { + TK_KEYWORD = true, TK_NAME = true, TK_NUMBER = true, + TK_STRING = true, TK_LSTRING = true, + } + if not option["opt-comments"] then + ACCEPT.TK_COMMENT = true + ACCEPT.TK_LCOMMENT = true + end + -------------------------------------------------------------------- + -- create a new table and remove any original locals by filtering + -------------------------------------------------------------------- + local filtered = {} + for i = 1, #toklist do + filtered[i] = seminfolist[i] + end + for i = 1, #localinfo do -- enumerate local info table + local obj = localinfo[i] + local xref = obj.xref + for j = 1, obj.xcount do + local p = xref[j] + filtered[p] = "" -- remove locals + end + end + -------------------------------------------------------------------- + local freq = {} -- reset symbol frequency table + for i = 0, 255 do freq[i] = 0 end + for i = 1, #toklist do -- gather symbol frequency + local tok, info = toklist[i], filtered[i] + if ACCEPT[tok] then + for j = 1, #info do + local c = byte(info, j) + freq[c] = freq[c] + 1 + end + end--if + end--for + -------------------------------------------------------------------- + -- function to re-sort symbols according to actual frequencies + -------------------------------------------------------------------- + local function resort(symbols) + local symlist = {} + for i = 1, #symbols do -- prepare table to sort + local c = byte(symbols, i) + symlist[i] = { c = c, freq = freq[c], } + end + table.sort(symlist, -- sort selected symbols + function(v1, v2) + return v1.freq > v2.freq + end + ) + local charlist = {} -- reconstitute the string + for i = 1, #symlist do + charlist[i] = char(symlist[i].c) + end + return table.concat(charlist) + end + -------------------------------------------------------------------- + LETTERS = resort(LETTERS) -- change letter arrangement + ALPHANUM = resort(ALPHANUM) +end + +---------------------------------------------------------------------- +-- returns a string containing a new local variable name to use, and +-- a flag indicating whether it collides with a global variable +-- * trapping keywords and other names like 'self' is done elsewhere +---------------------------------------------------------------------- + +local function new_var_name() + local var + local cletters, calphanum = #LETTERS, #ALPHANUM + local v = var_new + if v < cletters then -- single char + v = v + 1 + var = string.sub(LETTERS, v, v) + else -- longer names + local range, sz = cletters, 1 -- calculate # chars fit + repeat + v = v - range + range = range * calphanum + sz = sz + 1 + until range > v + local n = v % cletters -- left side cycles faster + v = (v - n) / cletters -- do first char first + n = n + 1 + var = string.sub(LETTERS, n, n) + while sz > 1 do + local m = v % calphanum + v = (v - m) / calphanum + m = m + 1 + var = var..string.sub(ALPHANUM, m, m) + sz = sz - 1 + end + end + var_new = var_new + 1 + return var, globaluniq[var] ~= nil +end + +---------------------------------------------------------------------- +-- calculate and print some statistics +-- * probably better in main source, put here for now +---------------------------------------------------------------------- + +local function stats_summary(globaluniq, localuniq, afteruniq, option) + local print = print or base.print + local fmt = string.format + local opt_details = option.DETAILS + local uniq_g , uniq_li, uniq_lo, uniq_ti, uniq_to, -- stats needed + decl_g, decl_li, decl_lo, decl_ti, decl_to, + token_g, token_li, token_lo, token_ti, token_to, + size_g, size_li, size_lo, size_ti, size_to + = 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 + local function avg(c, l) -- safe average function + if c == 0 then return 0 end + return l / c + end + -------------------------------------------------------------------- + -- collect statistics (note: globals do not have declarations!) + -------------------------------------------------------------------- + for name, uniq in base.pairs(globaluniq) do + uniq_g = uniq_g + 1 + token_g = token_g + uniq.token + size_g = size_g + uniq.size + end + for name, uniq in base.pairs(localuniq) do + uniq_li = uniq_li + 1 + decl_li = decl_li + uniq.decl + token_li = token_li + uniq.token + size_li = size_li + uniq.size + end + for name, uniq in base.pairs(afteruniq) do + uniq_lo = uniq_lo + 1 + decl_lo = decl_lo + uniq.decl + token_lo = token_lo + uniq.token + size_lo = size_lo + uniq.size + end + uniq_ti = uniq_g + uniq_li + decl_ti = decl_g + decl_li + token_ti = token_g + token_li + size_ti = size_g + size_li + uniq_to = uniq_g + uniq_lo + decl_to = decl_g + decl_lo + token_to = token_g + token_lo + size_to = size_g + size_lo + -------------------------------------------------------------------- + -- detailed stats: global list + -------------------------------------------------------------------- + if opt_details then + local sorted = {} -- sort table of unique global names by size + for name, uniq in base.pairs(globaluniq) do + uniq.name = name + sorted[#sorted + 1] = uniq + end + table.sort(sorted, + function(v1, v2) + return v1.size > v2.size + end + ) + local tabf1, tabf2 = "%8s%8s%10s %s", "%8d%8d%10.2f %s" + local hl = string.rep("-", 44) + print("*** global variable list (sorted by size) ***\n"..hl) + print(fmt(tabf1, "Token", "Input", "Input", "Global")) + print(fmt(tabf1, "Count", "Bytes", "Average", "Name")) + print(hl) + for i = 1, #sorted do + local uniq = sorted[i] + print(fmt(tabf2, uniq.token, uniq.size, avg(uniq.token, uniq.size), uniq.name)) + end + print(hl) + print(fmt(tabf2, token_g, size_g, avg(token_g, size_g), "TOTAL")) + print(hl.."\n") + -------------------------------------------------------------------- + -- detailed stats: local list + -------------------------------------------------------------------- + local tabf1, tabf2 = "%8s%8s%8s%10s%8s%10s %s", "%8d%8d%8d%10.2f%8d%10.2f %s" + local hl = string.rep("-", 70) + print("*** local variable list (sorted by allocation order) ***\n"..hl) + print(fmt(tabf1, "Decl.", "Token", "Input", "Input", "Output", "Output", "Global")) + print(fmt(tabf1, "Count", "Count", "Bytes", "Average", "Bytes", "Average", "Name")) + print(hl) + for i = 1, #varlist do -- iterate according to order assigned + local name = varlist[i] + local uniq = afteruniq[name] + local old_t, old_s = 0, 0 + for j = 1, #localinfo do -- find corresponding old names and calculate + local obj = localinfo[j] + if obj.name == name then + old_t = old_t + obj.xcount + old_s = old_s + obj.xcount * #obj.oldname + end + end + print(fmt(tabf2, uniq.decl, uniq.token, old_s, avg(old_t, old_s), + uniq.size, avg(uniq.token, uniq.size), name)) + end + print(hl) + print(fmt(tabf2, decl_lo, token_lo, size_li, avg(token_li, size_li), + size_lo, avg(token_lo, size_lo), "TOTAL")) + print(hl.."\n") + end--if opt_details + -------------------------------------------------------------------- + -- display output + -------------------------------------------------------------------- + local tabf1, tabf2 = "%-16s%8s%8s%8s%8s%10s", "%-16s%8d%8d%8d%8d%10.2f" + local hl = string.rep("-", 58) + print("*** local variable optimization summary ***\n"..hl) + print(fmt(tabf1, "Variable", "Unique", "Decl.", "Token", "Size", "Average")) + print(fmt(tabf1, "Types", "Names", "Count", "Count", "Bytes", "Bytes")) + print(hl) + print(fmt(tabf2, "Global", uniq_g, decl_g, token_g, size_g, avg(token_g, size_g))) + print(hl) + print(fmt(tabf2, "Local (in)", uniq_li, decl_li, token_li, size_li, avg(token_li, size_li))) + print(fmt(tabf2, "TOTAL (in)", uniq_ti, decl_ti, token_ti, size_ti, avg(token_ti, size_ti))) + print(hl) + print(fmt(tabf2, "Local (out)", uniq_lo, decl_lo, token_lo, size_lo, avg(token_lo, size_lo))) + print(fmt(tabf2, "TOTAL (out)", uniq_to, decl_to, token_to, size_to, avg(token_to, size_to))) + print(hl.."\n") +end + +---------------------------------------------------------------------- +-- main entry point +-- * does only local variable optimization for now +---------------------------------------------------------------------- + +function optimize(option, _toklist, _seminfolist, _globalinfo, _localinfo) + -- set tables + toklist, seminfolist, globalinfo, localinfo + = _toklist, _seminfolist, _globalinfo, _localinfo + var_new = 0 -- reset variable name allocator + varlist = {} + ------------------------------------------------------------------ + -- preprocess global/local tables, handle entropy reduction + ------------------------------------------------------------------ + globaluniq = preprocess(globalinfo) + localuniq = preprocess(localinfo) + if option["opt-entropy"] then -- for entropy improvement + recalc_for_entropy(option) + end + ------------------------------------------------------------------ + -- build initial declared object table, then sort according to + -- token count, this might help assign more tokens to more common + -- variable names such as 'e' thus possibly reducing entropy + -- * an object knows its localinfo index via its 'id' field + -- * special handling for "self" special local (parameter) here + ------------------------------------------------------------------ + local object = {} + for i = 1, #localinfo do + object[i] = localinfo[i] + end + table.sort(object, -- sort largest first + function(v1, v2) + return v1.xcount > v2.xcount + end + ) + ------------------------------------------------------------------ + -- the special "self" function parameters must be preserved + -- * the allocator below will never use "self", so it is safe to + -- keep those implicit declarations as-is + ------------------------------------------------------------------ + local temp, j, gotself = {}, 1, false + for i = 1, #object do + local obj = object[i] + if not obj.isself then + temp[j] = obj + j = j + 1 + else + gotself = true + end + end + object = temp + ------------------------------------------------------------------ + -- a simple first-come first-served heuristic name allocator, + -- note that this is in no way optimal... + -- * each object is a local variable declaration plus existence + -- * the aim is to assign short names to as many tokens as possible, + -- so the following tries to maximize name reuse + -- * note that we preserve sort order + ------------------------------------------------------------------ + local nobject = #object + while nobject > 0 do + local varname, gcollide + repeat + varname, gcollide = new_var_name() -- collect a variable name + until not SKIP_NAME[varname] -- skip all special names + varlist[#varlist + 1] = varname -- keep a list + local oleft = nobject + ------------------------------------------------------------------ + -- if variable name collides with an existing global, the name + -- cannot be used by a local when the name is accessed as a global + -- during which the local is alive (between 'act' to 'rem'), so + -- we drop objects that collides with the corresponding global + ------------------------------------------------------------------ + if gcollide then + -- find the xref table of the global + local gref = globalinfo[globaluniq[varname].id].xref + local ngref = #gref + -- enumerate for all current objects; all are valid at this point + for i = 1, nobject do + local obj = object[i] + local act, rem = obj.act, obj.rem -- 'live' range of local + -- if rem < 0, it is a -id to a local that had the same name + -- so follow rem to extend it; does this make sense? + while rem < 0 do + rem = localinfo[-rem].rem + end + local drop + for j = 1, ngref do + local p = gref[j] + if p >= act and p <= rem then drop = true end -- in range? + end + if drop then + obj.skip = true + oleft = oleft - 1 + end + end--for + end--if gcollide + ------------------------------------------------------------------ + -- now the first unassigned local (since it's sorted) will be the + -- one with the most tokens to rename, so we set this one and then + -- eliminate all others that collides, then any locals that left + -- can then reuse the same variable name; this is repeated until + -- all local declaration that can use this name is assigned + -- * the criteria for local-local reuse/collision is: + -- A is the local with a name already assigned + -- B is the unassigned local under consideration + -- => anytime A is accessed, it cannot be when B is 'live' + -- => to speed up things, we have first/last accesses noted + ------------------------------------------------------------------ + while oleft > 0 do + local i = 1 + while object[i].skip do -- scan for first object + i = i + 1 + end + ------------------------------------------------------------------ + -- first object is free for assignment of the variable name + -- [first,last] gives the access range for collision checking + ------------------------------------------------------------------ + oleft = oleft - 1 + local obja = object[i] + i = i + 1 + obja.newname = varname + obja.skip = true + obja.done = true + local first, last = obja.first, obja.last + local xref = obja.xref + ------------------------------------------------------------------ + -- then, scan all the rest and drop those colliding + -- if A was never accessed then it'll never collide with anything + -- otherwise trivial skip if: + -- * B was activated after A's last access (last < act) + -- * B was removed before A's first access (first > rem) + -- if not, see detailed skip below... + ------------------------------------------------------------------ + if first and oleft > 0 then -- must have at least 1 access + local scanleft = oleft + while scanleft > 0 do + while object[i].skip do -- next valid object + i = i + 1 + end + scanleft = scanleft - 1 + local objb = object[i] + i = i + 1 + local act, rem = objb.act, objb.rem -- live range of B + -- if rem < 0, extend range of rem thru' following local + while rem < 0 do + rem = localinfo[-rem].rem + end + -------------------------------------------------------- + if not(last < act or first > rem) then -- possible collision + -------------------------------------------------------- + -- B is activated later than A or at the same statement, + -- this means for no collision, A cannot be accessed when B + -- is alive, since B overrides A (or is a peer) + -------------------------------------------------------- + if act >= obja.act then + for j = 1, obja.xcount do -- ... then check every access + local p = xref[j] + if p >= act and p <= rem then -- A accessed when B live! + oleft = oleft - 1 + objb.skip = true + break + end + end--for + -------------------------------------------------------- + -- A is activated later than B, this means for no collision, + -- A's access is okay since it overrides B, but B's last + -- access need to be earlier than A's activation time + -------------------------------------------------------- + else + if objb.last and objb.last >= obja.act then + oleft = oleft - 1 + objb.skip = true + end + end + end + -------------------------------------------------------- + if oleft == 0 then break end + end + end--if first + ------------------------------------------------------------------ + end--while + ------------------------------------------------------------------ + -- after assigning all possible locals to one variable name, the + -- unassigned locals/objects have the skip field reset and the table + -- is compacted, to hopefully reduce iteration time + ------------------------------------------------------------------ + local temp, j = {}, 1 + for i = 1, nobject do + local obj = object[i] + if not obj.done then + obj.skip = false + temp[j] = obj + j = j + 1 + end + end + object = temp -- new compacted object table + nobject = #object -- objects left to process + ------------------------------------------------------------------ + end--while + ------------------------------------------------------------------ + -- after assigning all locals with new variable names, we can + -- patch in the new names, and reprocess to get 'after' stats + ------------------------------------------------------------------ + for i = 1, #localinfo do -- enumerate all locals + local obj = localinfo[i] + local xref = obj.xref + if obj.newname then -- if got new name, patch it in + for j = 1, obj.xcount do + local p = xref[j] -- xrefs indexes the token list + seminfolist[p] = obj.newname + end + obj.name, obj.oldname -- adjust names + = obj.newname, obj.name + else + obj.oldname = obj.name -- for cases like 'self' + end + end + ------------------------------------------------------------------ + -- deal with statistics output + ------------------------------------------------------------------ + if gotself then -- add 'self' to end of list + varlist[#varlist + 1] = "self" + end + local afteruniq = preprocess(localinfo) + stats_summary(globaluniq, localuniq, afteruniq, option) + ------------------------------------------------------------------ +end |